org.apache.lucene.analysis.standard.StandardAnalyzer Maven / Gradle / Ivy
package org.apache.lucene.analysis.standard;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import org.apache.lucene.analysis.*;
import org.apache.lucene.analysis.core.LowerCaseFilter;
import org.apache.lucene.analysis.core.StopAnalyzer;
import org.apache.lucene.analysis.core.StopFilter;
import org.apache.lucene.analysis.util.CharArraySet;
import org.apache.lucene.analysis.util.StopwordAnalyzerBase;
import org.apache.lucene.analysis.util.WordlistLoader;
import org.apache.lucene.util.Version;
import java.io.File;
import java.io.IOException;
import java.io.Reader;
/**
* Filters {@link StandardTokenizer} with {@link StandardFilter}, {@link
* LowerCaseFilter} and {@link StopFilter}, using a list of
* English stop words.
*
*
* You must specify the required {@link Version}
* compatibility when creating StandardAnalyzer:
*
* - As of 3.4, Hiragana and Han characters are no longer wrongly split
* from their combining characters. If you use a previous version number,
* you get the exact broken behavior for backwards compatibility.
*
- As of 3.1, StandardTokenizer implements Unicode text segmentation,
* and StopFilter correctly handles Unicode 4.0 supplementary characters
* in stopwords. {@link ClassicTokenizer} and {@link ClassicAnalyzer}
* are the pre-3.1 implementations of StandardTokenizer and
* StandardAnalyzer.
*
- As of 2.9, StopFilter preserves position increments
*
- As of 2.4, Tokens incorrectly identified as acronyms
* are corrected (see LUCENE-1068)
*
*/
public final class StandardAnalyzer extends StopwordAnalyzerBase {
/** Default maximum allowed token length */
public static final int DEFAULT_MAX_TOKEN_LENGTH = 255;
private int maxTokenLength = DEFAULT_MAX_TOKEN_LENGTH;
/** An unmodifiable set containing some common English words that are usually not
useful for searching. */
public static final CharArraySet STOP_WORDS_SET = StopAnalyzer.ENGLISH_STOP_WORDS_SET;
/** Builds an analyzer with the given stop words.
* @param matchVersion Lucene version to match See {@link
* above}
* @param stopWords stop words */
public StandardAnalyzer(Version matchVersion, CharArraySet stopWords) {
super(matchVersion, stopWords);
}
/** Builds an analyzer with the default stop words ({@link
* #STOP_WORDS_SET}).
* @param matchVersion Lucene version to match See {@link
* above}
*/
public StandardAnalyzer(Version matchVersion) {
this(matchVersion, STOP_WORDS_SET);
}
/** Builds an analyzer with the stop words from the given reader.
* @see WordlistLoader#getWordSet(Reader, Version)
* @param matchVersion Lucene version to match See {@link
* above}
* @param stopwords Reader to read stop words from */
public StandardAnalyzer(Version matchVersion, Reader stopwords) throws IOException {
this(matchVersion, loadStopwordSet(stopwords, matchVersion));
}
/**
* Set maximum allowed token length. If a token is seen
* that exceeds this length then it is discarded. This
* setting only takes effect the next time tokenStream or
* tokenStream is called.
*/
public void setMaxTokenLength(int length) {
maxTokenLength = length;
}
/**
* @see #setMaxTokenLength
*/
public int getMaxTokenLength() {
return maxTokenLength;
}
@Override
protected TokenStreamComponents createComponents(final String fieldName, final Reader reader) {
final StandardTokenizer src = new StandardTokenizer(matchVersion, reader);
src.setMaxTokenLength(maxTokenLength);
TokenStream tok = new StandardFilter(matchVersion, src);
tok = new LowerCaseFilter(matchVersion, tok);
tok = new StopFilter(matchVersion, tok, stopwords);
return new TokenStreamComponents(src, tok) {
@Override
protected void setReader(final Reader reader) throws IOException {
src.setMaxTokenLength(StandardAnalyzer.this.maxTokenLength);
super.setReader(reader);
}
};
}
}